Cataract is a common ailment effecting the human eyes, especially the eyes of older people, and can lead to blindness. Removal of the clouded biological lens material (i.e., the natural lens) from the capsule of the lens of the affected eye will restore light perception (see also FIG. 1). Full rehabilitation, however, requires that the refractive power of the natural lens be replaced by some other means because the light rays no longer are focused on the retina when the natural lens is removed. Consequently, cataract extraction is a common ophthalmic surgical procedure performed in the United States in which the natural lenses is replaced with a prosthetic optical device such as corrective eye glasses, contact lens and/or intraocular lens, so useful vision can be restored to the operated eye.
In the somewhat distant past, the replacement of the refractive power of the natural lens was achieved by the use of corrective eyeglasses or contact lens. The eyeglasses and contacts, however, have limitations in such an application. Corrective eyeglasses, however, being located in front of the normal position of the human lens, can produce magnification that distorts the shape of viewed objects. Contact lenses cause less magnification and distortion, however, very old and very young patients frequently find handling and wearing these small lenses difficult.
As a result of these limitations, the treatment of cataracts has developed to include the implantation of an artificial lens, typically called an intraocular lens, in the eye to mimic the function of the original natural lens. With implanted intraocular lenses, there is little or no magnification or distortion. Also, there is no need to remove the intraocular lens from the eye or otherwise handle the lens. Generally, intraocular lenses provide good visual acuity at all times, even at night.
Intraocular lenses have definite advantages in terms of vision and convenience over the other methods of aphakic correction. Intraocular lens implantation surgery, however, is more traumatic than simple cataract extraction alone. The additional handling of the cornea and manipulation inside the anterior chamber during lens implantation add to the amount of trauma to the eye. Extreme care must be exercise to limit trauma to the cornea, structures of the anterior chamber, and other structures. In this microfine surgery uncommon agility on the part of even a skilled surgeon often is required. Space limitations in the eye, the required size of the lens once implanted, and considerable manipulations of the lenses during implantation by the surgeon can result in traumatic damage to the corneal endothelium and very often rupture of the posterior capsule by the novice. Damage to the corneal endothelium and rupture of the posterior capsule are complications considered serious.
Initially, the intraocular lens was a relatively rigid lens requiring a 7–8 mm incision to be made in the conjunctiva and sclera just outside the cornea so that the patient's lens can be removed and replaced with an implant intraocular lens. Incision length is dictated more by the size of the intraocular lens to be implanted than by the requirement of removing the patient's natural lens. For example, since the development of the phacoemulsification technique, the patient's natural lens can be removed using an ultrasonic instrument that requires a corneal incision of about 2–3 mm which is much smaller than is needed to insert a rigid intraocular lens.
Efforts to minimize overall intraocular lens size of the rigid lens, and hence reduce trauma, have concentrated on collapsing or folding haptic prior to insertion. Haptics, also called loops or feet, emanate from the lenses and are intended to support and fix the intraocular lens in the eye. Some attempts have been made to reduce the size of the central lenticular portion of intraocular lenses prior to insertion. Silicon lenses which can be folded and gel-type lenses which absorb intraocular fluid and subsequently expand do address the surgical trauma problem. Nevertheless, the incision required for these lenses, although less than the 7–8 mm length for solid intraocular lenses, is relatively large, about 4 mm in length.
A major concern of ophthalmic surgeons is choosing the correct refractive power for lenses. Patients risk additional surgery for lens removal and replacement if the choice of lens refractive power is too much in error. A risk commonly shared in the use of solid, silicon, and gel-type lenses is additional surgery since it is the only alternative for changing a refractive power too much in error. This concern about additional surgery and selecting refractive power becomes of particular concern when dealing with young patients because a rigid lens of the correct refractive power when implanted may not later correctly focus light entering the eye and passing to the retina due to the changing in the size and shape of the eyeball in very young patients as they mature.
As a result, other types of intraocular lens and delivery systems have been developed in which the lens is inserted into the eye in a deflated condition and following such insertion the lens is then inflated or expanded by injecting a liquid, gas or other material into a cavity within the lens. With these other types of intraocular lens, the lens is disposed at least in major part within some sort of insertion device and is forced out of the insertion device using a fluid or rigid member that essentially pushes or ejects the lens from the insertion device.
Also, with these types of intraocular lens one or more separate conduits, cannulas or tubules are provided that interconnects the interior cavity to an external source of the liquid, gas or other material to be injected. Thus, following, such ejection of the lens from the insertion device, the lens is inflated or expanded by flowing the liquid, gas or other material through the one or more conduits or tubules into the cavity. After inflation is completed, the connection with the external source is broken and the surgeon pushes the conduit(s) or tubule(s) attached to the lens into a portion of the eye in which the lens is located. It also must be located so that it does not occlude visual acuity. While such lens and delivery systems have been developed for purposes of reducing the size of the incision required for insertion of the lens, there have arisen complex lens folding issues and haptic breakage concerns. Illustration and description of such lens and/or delivery systems can be found in U.S. Pat. Nos. 4,822,360; 4,693,717; 4,685,921; 4,619,662; 4,585,457 and 4,373,218.
It thus would be desirable to provide a new and novel intraocular lens system as well as related devices and intraocular lens, so as to minimize haptic breakage and concerns with lens manipulation within the lens capsule. It would be particularly desirable to provide such systems, devices, lens and methods related thereto whereby such insertion can be achieved while using minimally sized incisions as in comparison to that for prior art techniques and lens. It also would be desirable to provide such a lens that provides a mechanism for selectively adjusting the refractive power of the lens by means of regulating the material being injected. It also would be yet more desirable to provide such a lens whereby the refractive power can be adjusted following implantation at a later time during the life of the patient to compensate for changing conditions of the eye. Such lens, insertion devices and systems preferably would be simple in construction than prior art devices, lens and systems and such methods would not be unduly complex as compared to prior art methods.